There are two genera of plant pararetroviruses, the Caulimovirus and the Badnavirus in the Caulimoviri-dae family. The genome organization can be considered as comprising the core replicon of polymerase (reverse transcriptase -I- RNaseH) and coat protein which is considered to organize the replication complex together with genes which adapt the replicon to the plant viral situation. These additional genes are best characterized in cauliflower mosaic virus (CaMV) in which the core replicon is encoded by open reading frame (ORF) IV giving the coat protein and ORF V the polymerase. The plant-adapting genes include the ORF I product which facilitates the movement of the virus from cell to cell through plasmodesmata, and the ORF II product which is disease epidemiology, RTBV-induced disease in rice is amenable to control strategies not relevant to the other badnavirus diseases. Breeding and selection of virus- or vector-resistant varieties is a prime option in the case of rice, but is less readily accomplished in clonally propagated crop plant hosts of other badna-viruses. Control of vector populations by cultural or chemical methods is also far more relevant to RTBV than to other badnaviruses.
See also: Plant pararetroviruses (Caulimoviridae): Caulimoviruses: general features, Caulimoviruses: molecular biology.
Cheng C-P, Lockhart, BEL and Olszewski NE (1996) The ORF I and II proteins of Commelina yellow mottle virus are virion-associated. Virology 223: 263.
Natural Resistance Engineered Resistance
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